Daniel Pulido

Amphiphilic cationic carbosilane-PEG dendrimers: synthesis and applications in gene therapy.

Here we synthesized carbosilane, generation 1 to 3, and PEG-based dendrons functionalized at the periphery with NHBoc groups and at the focal point with azide and alkyne moieties, respectively. The coupling of these two types of dendrons via click chemistry led to the formation of new hybrid dendrimers with two distinct moieties, the hydrophobic carbosilane and the hydrophilic PEG-based dendron. The protected dendrimers were transformed into cationic ammonium dendrimers. These unique amphiphilic dendrimers were studied as vectors for gene therapy against HIV in peripheral blood mononuclear cells (PBMC) and their performance was compared with that of a PEG-free carbosilane dendrimer. The presence of the PEG moiety afforded lower toxicities and evidenced a weaker interaction between dendrimers and siRNA when compared to the homodendrimer analogous. Both features, lower toxicity and lower dendriplex strength, are key properties for use of these vectors as carriers of nucleic material.

Lamellarin D Bioconjugates II: Synthesis and Cellular Internalization of Dendrimer and Nuclear Location Signal Derivatives

The design and synthesis of Lamellarin D conjugates with a nuclear localization signal peptide and a poly(ethylene glycol)-based dendrimer are described. Conjugates 1-4 were obtained in 8-84% overall yields from the corresponding protected Lamellarin D. Conjugates 1 and 4 are 1.4- to 3.3-fold more cytotoxic than the parent compound against three human tumor cell lines (MDA-MB-231 breast, A-549 lung, and HT-29 colon). Besides, conjugates 3 and 4 showed a decrease in activity potency in BJ skin fibroblasts, a normal cell culture. Cellular internalization was analyzed, and a nuclear distribution pattern was observed for 4, which contains a nuclear localization signaling sequence.

Multifunctional Nanovesicle-Bioactive Conjugates Prepared by a One-Step Scalable Method Using CO2-Expanded Solvents

The integration of therapeutic biomolecules, such as proteins and peptides, in nanovesicles is a widely used strategy to improve their stability and efficacy. However, the translation of these promising nanotherapeutics to clinical tests is still challenged by the complexity involved in the preparation of functional nanovesicles and their reproducibility, scalability, and cost production. Here we introduce a simple one-step methodology based on the use of CO2-expanded solvents to prepare multifunctional nanovesicle-bioactive conjugates. We demonstrate high vesicle-to-vesicle homogeneity in terms of size and lamellarity, batch-to-batch consistency, and reproducibility upon scaling-up. Importantly, the procedure is readily amenable to the integration/encapsulation of multiple components into the nanovesicles in a single step and yields sufficient quantities for clinical research. The simplicity, reproducibility, and scalability render this one-step fabrication process ideal for the rapid and low-cost translation of nanomedicine candidates from the bench to the clinic.

Multivalent dendrimers presenting spatially controlled clusters of binding epitopes in thermoresponsive hyaluronan hydrogels

The controlled presentation of biofunctionality is of key importance for hydrogel applications in cell-based regenerative medicine. Here, a versatile approach was demonstrated to present clustered binding epitopes in an injectable, thermoresponsive hydrogel. Well-defined multivalent dendrimers bearing four integrin binding sequences and an azido moiety were covalently grafted to propargylamine-derived hyaluronic acid (Hyal-pa) using copper-catalyzed alkyne-azide cycloaddition (CuAAC), and then combined with pN-modified hyaluronan (Hyal-pN). The dendrimers were prepared by synthesizing a bifunctional diethylenetriamine pentaacetic acid core with azido and NHBoc oligo(ethylene glycol) aminoethyl branches, then further conjugated with solid-phase synthesized RGDS and DGRS peptides. Azido terminated pN was synthesized by reversible addition-fragmentation chain transfer polymerization and reacted to Hyal-pa via CuAAC. Nuclear magnetic resonance (NMR), high performance liquid chromatography, size exclusion chromatography and mass spectroscopy proved that the dendrimers had well-defined size and were disubstituted. NMR and atomic absorption analysis confirmed the hyaluronan was affixed with dendrimers or pN. Rheological measurements demonstrated that dendrimers do not influence the elastic or viscous moduli of thermoresponsive hyaluronan compositions at a relevant biological concentration. Finally, human mesenchymal stromal cells were encapsulated in the biomaterial and cultured for 21days, demonstrating the faculty of this dendrimer-modified hydrogel as a molecular toolbox for tailoring the biofunctionality of thermoresponsive hyaluronan carriers for biomedical applications.

Injectable Hyaluronan Hydrogels with Peptide-Binding Dendrimers Modulate the Controlled Release of BMP-2 and TGF-β1

BMP-2 and TGF-β1 released from injectable thermoresponsive hydrogels are studied in the presence and absence of branched macromolecules bearing BMP-2 or TGF-β1 affinity binding peptides. The synthesized branched macromolecules and the gelling compositions before and after loading with either BMP-2 or TGF-β1 are characterized physico-chemically and show a significantly lower amount of proteins released in the presence of the affinity binding peptide macromolecules. This study illustrates the potential of affinity binding peptide functionalized dendrimers to modulate the local delivery and availability of growth factors important for musculoskeletal regeneration therapies.

α-Galactosidase-A Loaded-Nanoliposomes with Enhanced Enzymatic Activity and Intracellular Penetration

Lysosomal storage disorders (LSD) are caused by lysosomal dysfunction usually as a consequence of deficiency of a single enzyme required for the metabolism of macromolecules, such as lipids, glycoproteins, and mucopolysaccharides. For instance, the lack of α-galactosidase A (GLA) activity in Fabry disease patients causes the accumulation of glycosphingolipids in the vasculature leading to multiple organ pathology. Enzyme replacement therapy, which is the most common treatment of LSD, exhibits several drawbacks mainly related to the instability and low efficacy of the exogenously administered therapeutic enzyme. In this work, the unprecedented increased enzymatic activity and intracellular penetration achieved by the association of a human recombinant GLA to nanoliposomes functionalized with Arginine-Glycine-Aspartic acid (RGD) peptides is reported. Moreover, these new GLA loaded nanoliposomes lead to a higher efficacy in the reduction of the GLA substrate named globotriasylceramide in a cellular model of Fabry disease, than that achieved by the same concentration of the free enzyme. The preparation of these new liposomal formulations by DELOS-SUSP, based on the depressurization of a CO2 -expanded liquid organic solution, shows the great potential of this CO2 -based methodology for the one-step production of protein-nanoliposome conjugates as bioactive nanomaterials with therapeutic interest.

Controlling Multivalency and Multimodality: Up to Pentamodal Dendritic Platforms Based on Diethylenetriaminepentaacetic Acid Cores

A highly versatile synthetic strategy is described to generate multimodal and multivalent platforms based on a diethylenetriaminepentaacetic (DTPA) core. Compounds with different functionalization patterns, from mono- to pentamodal, have been prepared using robust and simple chemistry.

Solid-Phase Synthesis of Phenylalanine Containing Peptides Using a Traceless Triazene Linker

The use of a triazene function to anchor phenylalanine to a polymeric support through its side chain is reported. To prove the usefulness of this strategy in solid-phase peptide synthesis, several bioactive peptides have been prepared including cyclic, C-modified, and protected peptides. The triazene linkage is formed by coupling the diazonium salt of Fmoc-Phe(pNH(2))-OAllyl to a MBHA-polystyrene resin previously functionalized with isonipecotic acid (90%). Further assembly of the peptide chain, cleavage from the resin using 2-5% TFA in DCM, and reduction of the resulting diazonium salt of the peptide with FeSO(4)·7H(2)O in DMF afforded the desired products in high purities (73-94%).

Triazene as a Powerful Tool for Solid-Phase Derivatization of Phenylalanine Containing Peptides: Zygosporamide Analogues as a Proof of Concept

A novel method for the synthesis of para-substituted phenylalanine containing cyclic peptides is described. The main features of this strategy are the coupling of phenylalanine to the solid support through its side chain via a triazene linkage, on-resin cyclization of the peptide chain, cleavage of the cyclic peptide from the resin under mild acidic conditions and further transformation of the resulting diazonium salt. The usefulness of this approach is exemplified by the solid-phase synthesis of some derivatives of the naturally occurring cyclic depsipeptide zygosporamide.

Stimuli-Responsive Functionalization Strategies to Spatially and Temporally Control Surface Properties: Michael vs Diels–Alder Type Additions

Stimuli-responsive self-assembled monolayers (SAMs) are used to confer switchable physical, chemical, or biological properties to surfaces through the application of external stimuli. To obtain spatially and temporally tunable surfaces, we present microcontact printed SAMs of a hydroquinone molecule that are used as a dynamic interface to immobilize different functional molecules either via Diels-Alder or Michael thiol addition reactions upon the application of a low potential. In spite of the use of such reactions and the potential applicability of the resulting surfaces in different fields ranging from sensing to biomedicine through data storage or cleanup, a direct comparison of the two functionalization strategies on a surface has not yet been performed. Although the Michael thiol addition requires molecules that are commercial or easy to synthesize in comparison with the cyclopentadiene derivatives needed for the Diels-Alder reaction, the latter reaction produces more homogeneous coverages under similar experimental conditions.